Zillow slides following new Citron Research report

|About: Zillow Group, Inc. (Z)|By:, SA News Editor

In a report (.pdf) modestly described as "the most comprehensive and thoughtful piece on Zillow (Z -3.1%) ever published," Citron Research declares the online/mobile real estate platform's Q2 a "complete disaster," argues its rapid top-line growth is only due to skyrocketing sales/marketing spend (now 70% of revenue), and declares Zillow lacks the operating leverage of a Google, Facebook, or LinkedIn.

Citron also notes Zillow only has an estimated 13.5% share of real estate site Web traffic (no site has a dominant share), highlights recent insider selling, and declares social media usage by realtors is "killing" the company (Premier Agent sub growth is nonetheless quite strong).

Citron first took aim at Zillow in Sep. '12, when shares were trading at $44.41. They're up 114% since then.